Channel Optimization in Half Duplex Communications Systems

ABSTRACT

Channel Optimization in Half Duplex Communications Systems is provided herein. Methods may include obtaining at a first terminal, radio frequency (RF) spectral information local to the first terminal, analyzing at the first terminal, RF spectral information for a second terminal that is not co-located with the first terminal, transmitting data to the second terminal on a second terminal optimal frequency band, and receiving data from the second terminal on the first terminal optimal frequency band, where the first terminal optimal frequency being based upon the RF spectral information local to the first terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims the benefit of, and is acontinuation of, U.S. patent application Ser. No. 14/325,307 filed onJul. 7, 2014, entitled “Channel Optimization in Half DuplexCommunications Systems”, which claims the benefit of, and is acontinuation of, U.S. patent application Ser. No. 14/164,081 filed onJan. 24, 2014, entitled “Channel Optimization in Half DuplexCommunications Systems”, all of which are hereby incorporated byreference herein in their entirety including all references citedtherein.

FIELD OF THE TECHNOLOGY

Embodiments of the disclosure relate to the wireless radio systems. Morespecifically, but not by way of limitation, the present technologyincludes dynamic channel selection in a half-duplex (HDX) mode withexplicit radio frequency (RF) spectrum feedback from a remote device,which allows a local device to select a Modulation and Coding Scheme(MCS) that maximizes the throughput and improves link reliability.

BACKGROUND OF THE DISCLOSURE

Carrier sensing, which is a fundamental medium access protocol for IEEE802.11 Distributed Coordination Function (DCF) devices, may functionpoorly when the RF environment at the transmitter and receiver arevastly different. For example, a terminal such as a transmitter beginssending a frame after determining a medium is free, but highinterference and noise levels at the receiver may cause the frame to bereceived erroneously at the intended receiving terminal. Retransmissionof the same data may degrade link throughput even further. The exchangeof Request-To-Send (RTS) and Clear-To-Send (CTS) frames before sendingof the data frames is intended to mitigate this problem. However, thesending of RTS and CTS frames for every data frame is inefficientparticularly for wireless links, and even further over large distances,leading to long transmission latency.

Another problem with an IEEE 802.11 DCF based medium access protocol isthat it requires terminal devices on both sides of a wireless link tooperate on the same channel for transmissions and receptions since aClear Channel Assessment (CCA) needs to be performed before any frameexchange sequences can be initiated. In a congested RF environment,there may be no single frequency band available for the wireless link.In addition, when the transmitter and receiver are separated by a longdistance their respective local radio environments are likely to besignificantly different, further reducing the likelihood of a singlefrequency band being optimal for both the forward and reverse wirelesslinks.

SUMMARY OF THE DISCLOSURE

According to some embodiments, the present technology may be directed toa method for transmitting data between network devices using channeloptimization in half duplex communications. The method may include: (a)obtaining at a first terminal, radio frequency (RF) spectral informationlocal to the first terminal; (b) analyzing at the first terminal, RFspectral information for a second terminal that is not co-located withthe first terminal; (c) transmitting data to the second terminal on asecond terminal optimal frequency band; and (d) receiving data from thesecond terminal on the first terminal optimal frequency band, the firstterminal optimal frequency being based upon the RF spectral informationlocal to the first terminal.

According to other embodiments, the present technology may be directedto a network coordinator for a network using time division duplexing ortime division multiple access. The network coordinator may include: (a)a processor; and (b) a memory for storing executable instructions, theprocessor executing the instructions to perform operations comprising:(i) establishing a wireless link with a plurality of terminal devices;(ii) receiving from the plurality of terminal devices, radio frequency(RF) spectral information; (iii) exchanging RF spectral informationbetween the plurality of terminal devices; and (iv) negotiating afrequency band for each of the plurality of terminal devices such that aproduct or a sum of a forward link and a reverse link throughput foreach plurality of terminal devices is jointly maximized on the wirelesslink, the forward and reverse link throughput being determined from ananalysis of the radio frequency (RF) spectral information for theplurality of terminal devices.

According to additional embodiments, the present technology may bedirected to a dual channel network device, comprising: (a) a timedivision duplexing interface for transmitting or receiving data on afirst channel; (b) a time division duplexing and frequency divisionduplexing interface for transmitting or receiving data on a secondchannel; (c) a processor; and (d) a memory for storing executableinstructions, the processor executing the instructions to performoperations comprising: (i) determining radio frequency (RF) spectralinformation local to the device; (ii) selecting at the device an optimalfrequency band for the first channel based upon the RF spectralinformation; (iii) selecting at the device an optimal frequency band forthe second channel based upon the RF spectral information; (iv)transmitting management frames that include the optimal frequency bandfor the first channel and the optimal frequency band for the secondchannel to one or more additional devices on a network; and (v)receiving data from the one or more devices on either of the first andsecond channels.

According to additional embodiments, the present technology may bedirected to a terminal device having (a) a processor; and (b) a memoryfor storing executable instructions, wherein execution of theinstructions causes the processor to: (i) determine radio frequency (RF)spectral information local to the terminal device; (ii) analyze spectralinformation for one or more additional terminals in a network that arenot co-located with the first terminal; (iii) determine an optimalfrequency band for each of the one or more additional terminals; (iv)transmit data to the one or more additional terminals using the optimalfrequency bands; and (v) receive data from the one or more additionalterminals on a device optimal frequency band that is based upon the RFspectral information local to the terminal device.

According to other embodiments, the present technology may be directedto a non-transitory computer readable storage media that includesinstructions for transmitting data between network devices using channeloptimization in half duplex communications. The method may include: (a)obtaining at a first terminal, radio frequency (RF) spectral informationlocal to the first terminal; (b) analyzing at the first terminal, RFspectral information for a second terminal that is not co-located withthe first terminal; (c) transmitting data to the second terminal on asecond terminal optimal frequency band; and (d) receiving data from thesecond terminal on the first terminal optimal frequency band, the firstterminal optimal frequency being based upon the RF spectral informationlocal to the first terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, together with the detailed description below, are incorporated inand form part of the specification, and serve to further illustrateembodiments of concepts that include the claimed disclosure, and explainvarious principles and advantages of those embodiments.

The methods and systems disclosed herein have been represented whereappropriate by conventional symbols in the drawings, showing only thosespecific details that are pertinent to understanding the embodiments ofthe present disclosure so as not to obscure the disclosure with detailsthat will be readily apparent to those of ordinary skill in the arthaving the benefit of the description herein.

FIG. 1A is an exemplary wireless network, constructed in accordance withthe present disclosure;

FIG. 1B is another exemplary wireless network, constructed in accordancewith the present technology;

FIG. 2 illustrates two terminal devices communicating together using apure Time Division Duplexing (TDD) mode of operation;

FIG. 3 illustrates three terminal devices communicating with one anotherusing Time Division Multiple Access (TDMA) and Frequency DivisionDuplexing (FDD) mode of operation;

FIG. 4 is a graphical representation of local terminal and remoteterminal RF spectrum profiles;

FIG. 5A illustrates an exemplary wireless system comprising apoint-to-multipoint arrangement of network terminals, having a hybridTDMA/FDD network topology;

FIG. 5B illustrates an exemplary wireless system comprising co-locatedarrangement of network terminals, having a hybrid TDMA/FDD networktopology;

FIG. 6 is a signal flow diagram illustrating a channel optimizationmethod executed between two terminals of a wireless network;

FIG. 7 is a signal flow diagram illustrating a channel optimizationmethod executed by a network coordinator, mediating communicationsbetween two terminals of a wireless network;

FIG. 8 is an exemplary method for transmitting data between networkdevices using channel optimization in half duplex communications;

FIG. 9 is an exemplary method for transmitting data between networkdevices using channel optimization in half duplex communications;

FIG. 10 is a schematic diagram of a method of channel optimizationexecuted by dual channel network devices (e.g., terminals);

FIG. 11 is a graphical plot of time-averaged interference plus noiseversus frequency band at two locations, each associated with a terminaldevice;

FIG. 12 is a graphical plot of received signal to noise ration versusfrequency bands at the two locations;

FIG. 13 is a graphical representation of available 80 MHz with number ofspatial streams (NSS) of 2 and an effective rate for different frequencybands at the two locations; and

FIG. 14 illustrates an exemplary computing system that may be used toimplement embodiments according to the present technology.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the disclosure. It will be apparent, however, to oneskilled in the art, that the disclosure may be practiced without thesespecific details. In other instances, structures and devices are shownat block diagram form only in order to avoid obscuring the disclosure.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” or“according to one embodiment” (or other phrases having similar import)at various places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments. Furthermore, depending on the context ofdiscussion herein, a singular term may include its plural forms and aplural term may include its singular form. Similarly, a hyphenated term(e.g., “on-demand”) may be occasionally interchangeably used with itsnon-hyphenated version (e.g., “on demand”), a capitalized entry (e.g.,“Software”) may be interchangeably used with its non-capitalized version(e.g., “software”), a plural term may be indicated with or without anapostrophe (e.g., PE's or PEs), and an italicized term (e.g., “N+1”) maybe interchangeably used with its non-italicized version (e.g., “N+1”).Such occasional interchangeable uses shall not be consideredinconsistent with each other.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

It is noted at the outset that the terms “coupled,” “connected”,“connecting,” “electrically connected,” etc., are used interchangeablyherein to generally refer to the condition of beingelectrically/electronically connected. Similarly, a first entity isconsidered to be in “communication” with a second entity (or entities)when the first entity electrically sends and/or receives (whetherthrough wireline or wireless means) information signals (whethercontaining data information or non-data/control information) to thesecond entity regardless of the type (analog or digital) of thosesignals. It is further noted that various figures (including componentdiagrams) shown and discussed herein are for illustrative purpose only,and are not drawn to scale.

Generally, the present disclosure relates to optimal, dynamic channelselection in a wireless network, where devices operate in a HDX modewith explicit RF spectrum feedback for terminal devices. RF spectrumfeedback allows the terminal devices to select a Modulation and CodingScheme (MCS) that maximizes the throughput and improves wireless linkreliability. These features reduce or eliminate the possibility ofhidden terminals and the inadequacy with carrier sensing for wirelesslinks with longer distance. These methodologies are particularlyadvantages in wireless links of long distance. In addition, dynamicchannel selection allows for adaptation within wireless links inresponse to local changes in the wireless medium and the physicalsurroundings, allowing continued optimal communications in light ofthese changes.

The decoupling and use of different frequency bands for transmission andreception allows the overall throughput to be further optimized, sincethe RF spectrum can be vastly different and/or congested on both sidesof a wireless link(s). In such situations, a reasonably good frequencyband may not be available for pure TDD or TDMA mode of operation. Whenterminal devices can select a different frequency band for both transmitand receive communications, the selection of frequency band(s) maymaximize throughput in both directions. Furthermore, this also increasesreliability of the wireless link, since it is less probable that apotential interferer may overlap both frequency bands for transmit andreceive at the same time.

The present technology contemplates various systems that dynamicallyselect the operating frequency band(s) for transmission or reception ofradio signals for half-duplex (HDX) communications. The choice offrequency band(s) used for transmission or reception of radio signalscan be identical or different. By exchanging locally measured RadioFrequency (RF) spectra, a device on either side of the wireless link candynamically select operating frequency band(s) for transmission andreception of radio signals that maximizes the overall link throughputand reliability.

It will be understood that devices in a HDX (half duplex) wirelesssystem are provisioned with non-overlapping periods of time fortransmission of radio signals. These can be based on Time DivisionDuplex (TDD) for point-to-point systems or Time Division Multiple Access(TDMA) for point-to-multipoint systems. The start and duration of eachtransmission period can be signaled to the device in three differentways, such as carrier sensing, token passing between devices, orcoordinated by an external entity (e.g., GPS clock, master device,etc.).

Each terminal device measures its local RF spectra, either on a periodictime interval, or when triggered by a loss of signal quality, or uponthe request of a remote device, such as another terminal device or anetwork coordinator. A terminal device then either sends local raw RFspectra information, or the preferred frequency band(s) for reception ofradio signals information to the opposing terminal device. A terminaldevice may select an optimal frequency band for transmissions eitherbased on the raw RF spectra information received, or adopt the preferredfrequency band(s) indicated. On each terminal device, the choice offrequency band(s) for transmission or reception of radio signals isselected separately based on the frequency band(s) that maximizes linkthroughput; as a result, different frequency band(s) can be selected fortransmission and reception.

For pure TDD or TDMA modes of operation, a frequency band is selectedsuch the product of the forward and reverse link throughput ismaximized. See FIG. 4 for selected frequency bands for both remote andlocal (e.g., first and second) terminal device, which illustrate a pureTDD mode of operation. A first optimal frequency band 405 is illustratedfor a first terminal 105 as well as a second optimal frequency band 410is illustrated for a second terminal 110. It is noteworthy that theoptimal frequency bands for both the first and second terminals 105 and110 change over time, as indicated by the trend lines. In time periodswhere the first and second optimal frequency bands coincide, such asduring interval 415, the terminal devices may operate in a pure TDDmode. It is also noteworthy that both the first and second terminals 105and 110 are utilizing a TDD/FDD mode of operation, where both terminalsare configured to utilize both time division and frequency division.Thus, when the optimal frequencies for the devices coincide, there isonly a need for the devices to perform time division with theircommunications. That is, the terminals are both operating optimally onthe same channel/frequency.

Another problem with an IEEE 802.11 DCF based medium access protocol isthat it requires terminal devices on both sides of a wireless link tooperate on the same channel for transmissions and receptions since aclear channel assessment (CCA) needs to be performed before any frameexchange sequences can be initiated. In a congested RF environment theremay be no single frequency band available for the wireless link.

Definitions and Terms

A Time Division Duplex (TDD) wireless system is a point-to-point systemcomprising of a pair of terminal devices that can send radio signals andcommunicate with each other in both directions. Only one terminal devicecan transmit a radio signal at any one time.

A Time Division Multiple Access (TDMA) wireless system is apoint-to-multipoint system comprising a group of terminal devices thatcan send radio signals and communicate with one another. Only oneterminal device can transmit a radio signal at any one time.

A transmission period is defined as duration of time where a terminaldevice in a TDD or TDMA systems transmits a radio signal. The start andduration of each transmission period can be indicated to the terminaldevice by carrier sensing, token passing between devices, or coordinatedby an external entity (e.g., GPS, master device, etc.).

A network coordinator coordinates and schedules transmission periods andfrequency bands for all transmission and reception of radio signals in awireless network. This function can be physically located in a singledevice or distributed across several devices, such as the terminaldevices of a wireless network.

A pure TDD or TDMA mode of operation is when terminal devicescommunicate wirelessly with one another in transmission periodsindicated, and the operating frequency bands for transmission andreception of radio signals are identical. Exemplary pure TDD or TDMAoperations are illustrated in FIG. 2. A terminal device 105 transmitsand receives during opposing transmission periods from a second terminaldevice 110, using the same frequency f1.

A TDD/FDD (Frequency Division Duplex) or TDMA/FDD mode of operation iswhen terminal devices communicate wirelessly with one another in theindicated transmission periods, and the operating frequency bands fortransmission and reception of radio signals can be different. An exampleof pure TDD/FDD or TDMA/FDD operations is illustrated in FIG. 3.Terminal devices 105, 110, and 111, each transmit and receive signalsaccording to the arrangement provided. It is noteworthy that for eachtransmit and receive transmission period, two of the three terminaldevices may communicate with one another on a particular frequency band.

A RF spectrum scan is a system process where a first terminalperiodically measures the local RF spectrum over the all availablefrequency bands, and generates a measurement report that is then sent toa second (or more) terminal. Alternatively, the first terminal may usethe measurement report to select a preferred frequency band(s), and sendthis preference to the second terminal.

The terms terminal or terminal device may be used interchangeablyherein, and may include, for example, an RF radio, such as a wirelesstransceiver, a User Equipment or communications device, such as cellulartelephone, or any other device that is capable of transmitting orreceiving RF signals that would be known to one of ordinary skill in theart with the present disclosure before them.

FIG. 1A illustrates an exemplary network 100A that includes networkdevices. In this embodiment, the network devices include a firstterminal 105 and a second terminal 110. It will be understood that thefirst and second terminal devices 105 and 110 may be constructedsimilarly to one another. In other instances, the first and secondterminal devices may be dissimilar to one another, although both thefirst and second terminal devices 105 and 110 may both include aprocessor 115 and a memory 120 for storing executable instructions. Theexecutable instructions that are stored in memory 120 may be executed bythe processor 115 to perform one or more of the various methods ofchannel optimization as described herein. Also, each of the devicesincludes a communications interface 125 that interfaces with a wirelesslink 130 that communicatively couples the first and second terminaldevices 105 and 110.

While FIG. 1A illustrates a first and second terminal devices 105 and110, the network 100A may include any number of terminal devices. Aswill be described herein, the network may include a point-to-multipointarrangement of terminal devices or an arrangement of terminal deviceswhere a portion of the terminal devices are co-located with one another(see FIGS. 5A and 5B).

Spectrum Monitoring

Each of the terminal devices 105 and 110 performs a RF spectrum scan oftheir local RF spectrum periodically for any of: (a) received Signal toNoise Ratio (SINR), (b) Error Vector Magnitude (EVM), (c) interferenceplus noise power spectrum, and (d) overlapping Basic Service Set (OBSS)traffic activity. The measurement for these parameters, with theexception of OBSS traffic activity, can be performed in any frequencybands permitted by local regulatory rules. For OBSS activity,measurement may occur by monitoring a count of beacons or any IEEE802.11 frames in each of the IEEE 802.11 channels.

Alternatively, a terminal device may process the RF spectra informationlocally, select a preferred frequency band(s) for reception of radiosignals, and communicate that information to one or more terminaldevices or a network coordinator 135 (see FIG. 1B).

This feedback report can include either the raw RF spectra information,or the preferred frequency band(s) for reception of radio signals. Insome embodiments, the feedback information may be encapsulated inproprietary management frame(s) and sent over an established wirelesslink to remote peer terminal devices at a periodic time interval, orwhen triggered by degradation in link quality, or upon the request by aremote peer terminal device.

Dynamic Channel Selection

As discussed in the overview section, the RF spectra can be vastlydifferent and/or congested on both sides of a wireless link. As will bedescribed in greater detail below, empirical data illustrating thewidely varying nature of RF spectral data for terminal devices, takenfrom actual measurements at two locations will be provided in graphicalformat in FIGS. 11-13.

For pure TDD or TDMA modes of operation, a frequency band is selectedsuch the product of the forward and reverse link throughput ismaximized. See FIG. 4 for selected frequency bands for both remote andlocal (e.g., first and second) terminal device, which illustrate a pureTDD mode of operation. A first optimal frequency band 405 is illustratedfor a first terminal 105 as well as a second optimal frequency band 410is illustrated for a second terminal 110. It is noteworthy that theoptimal frequency bands for both the first and second terminals 105 and110 change over time, as indicated by the trend lines. In time periodswhere the first and second optimal frequency bands coincide, such asduring interval 415, the terminal devices may operate in a pure TDDmode. It is also noteworthy that both the first and second terminals 105and 110 are utilizing a TDD/FDD mode of operation, where both terminalsare configured to utilize both time division and frequency division.Thus, when the optimal frequencies for the devices coincide, there isonly a need for the devices to perform time division with theircommunications. That is, the terminals are both operating optimally onthe same channel/frequency.

For TDD/FDD or TDMA/FDD mode of network operation, a frequency band maybe selected such that the sum of the forward and reverse link throughputis maximized. In other words, a local (first) terminal device selects afrequency band for transmission such that the interference plus SNIR atthe remote (second) terminal device is minimized or equivalently tomaximizing the received SINR. Also in this mode, the selection offrequency band used for transmission at both sides of the wireless linkcan be performed independently from one another. Advantageously, thefrequency bands for both the terminal devices are not required to beidentical to one another. A terminal device in this mode of operationwill be transmitting a frame at one frequency band, and receiving aframe at a different frequency band.

Advantageously, a mode of operation where TDD is overlaid with FDDcapabilities provides unique modes of operation for devices that areinherently limited. For example, most wireless radios are not designedto perform FDD modes of operation. Most of these devices are inherentlyhalf duplex devices and are not configured for full duplex operations.Full duplex radio creation is significantly more expensive than that ofhalf-duplex radios. Endowing half-duplex radio with the ability to layeran FDD mode of operation onto its inherent TDD mode will provideinterference mitigation due to use of FDD modes, while the radio mayoperate in TDD modes, when appropriate, to reduce operating cost.

Referring to FIG. 1B, which illustrates an exemplary network 100B forpracticing aspects of the present technology. In some embodiments, thenetwork 100B includes a network coordinator 135 that can establishwireless links, such as wireless link 130 with one or more remoteterminal devices. The network 100B may operate in a TDMA/FDD mode. Morespecifically, the network coordinator 135 exchanges local RF spectruminformation with each remote terminal device. This feedback informationcan include either the raw RF spectra information, or the preferredfrequency band(s) for reception of radio signals. Using this feedbackinformation, the network coordinator 135 negotiates with each group ofremote terminal devices the frequency band(s) for transmission andreception of radio signals that maximizes throughput and linkreliability.

Generally, the network coordinator 135 may include a processor 150 and amemory 155 for storing executable instructions. The processor 150executes the instructions stored in the memory 155 to perform variousmethods for establishing wireless links between terminal devices, wherethe wireless links are configured for optimal/maximum throughput usingthe channel optimization techniques described herein. The networkcoordinator 135 may also include a communications interface 160, such asan RF interface (i.e., an RF antenna and associated hardware) thatcommunicatively couples the network coordinator 135 with the first andsecond terminal devices 105 and 110. In some instances, the networkcoordinator 135 may be individually coupled to the terminal devices withseparate wireless links 165A and 165B, respectively.

It is noteworthy that a network coordinator 135 may include a terminaldevice that establishes an ad-hoc wireless network with one or moreremote terminal devices. In other instances, the network coordinator 135may include a centralized network device, such as a Call Session ControlFunction (CSCF) or service within a communications system that acts as acommunications intermediary between remote terminal devices.

See FIGS. 5A and 5B for examples of TDMA/FDD network topologies. Indetail, FIG. 5A illustrates a first terminal device 505, which iscoupled with a plurality of remote terminal devices 510A-C. After the RFspectrum analysis and exchange process, the first terminal device 505 isconfigured to receive signals from each of the plurality of remoteterminal devices 510A-C on a first optimal frequency band TX(f1), whiletransmitting signals to each of the remote terminal devices using aunique optimal frequency band. For example, the first terminal device505 transmits to the remote terminal device 510A on a frequency RX(f3),while transmitting to another remote terminal device 510E on a frequencyRX(f1), and yet another remote terminal device 510C on a frequencyRX(f2).

In FIG. 5B, two terminal devices 515A and 515E are co-located with oneanother, meaning that the two terminal devices 515A and 515E sharesimilar RF spectral information. Thus, remote terminal devices 520A and520B can transmit to the two terminal devices 515A and 515E using thesame frequency TX(f1). The two terminal devices 515A and 515E mayinclude co-located radios in a Multiple Input Multiple Output (MIMO)radio system.

Channel selection can be triggered dynamically by a terminal device(either local or remote) with the availability of a new measurementreport, or degradation in throughput performance beyond a threshold inthe current frequency band. For example, if a sum of local interferenceplus SINR indicates a reduction in throughput that is greater than 60%,a request for an updated RF spectral scan may be requested. When a moreoptimal frequency band is found, channel switch is achieved by arepeated exchange of management frames between terminal devices tocoordinate and schedule a channel switch at an indicated time in thefuture. RF spectrum monitoring and dynamic channel selection continuesto run throughout the existence of the wireless link.

Link Setup

A system of networked terminal devices operate in HDX mode either bycarrier sensing, token passing or coordinated by an external entity toexplicitly indicate transmission periods. Terminal devices communicatewirelessly with one another using these transmission periods. The systemcan be a point-to-point wireless link between two devices, or apoint-to-multipoint wireless network with a group of devices (see FIGS.5A and 5B). The negotiation to establish pure TDD or TDD/FDD modes ofoperation is achieved by an exchange of proprietary management framesbetween participating devices.

After establishing the mode of operation, participating terminal devicesstart the transfer of data frames in a HDX manner. In each transmissionperiod, only the terminal device assigned to that transmission period ispermitted to transmit a radio signal on an assigned, optimal frequencyband. The intended receiving terminal device (or devices) of this radiosignal switches to the frequency band at the start of the assignedtransmission period in anticipation of this radio signals. For pure TDDor TDMA mode of operation, terminal devices on both sides of thewireless link use the same frequency band for transmission of radiosignals, as described above. For TDD/FDD or TDMA/FDD modes of operation,terminal devices on both sides of a wireless link may use a differentfrequency band for transmission of radio signals.

FIG. 6 is a signal flow diagram of an exemplary optimal frequency bandexchange process and subsequent data transfer using the establishedoptimal frequency bands for a first terminal 105 and a second terminal110. Again, the first terminal 105 may transmit 605 either local RFspectral information to or desired optimal frequency band(s) to thesecond terminal 110. If the RF spectral information is transmitted, thesecond terminal 110 advantageously determines a first optimal frequencyband(s) for the first terminal 105. The same process 610 is conductedfor the second terminal 110 to determine a second optimal frequencyband. Once the optimal frequency bands have been established, the firstterminal 105 transmits 615 signals to the second terminal 110 on one ormore of the second optimal frequency bands, while the second terminal110 transmits 620 signals to the first terminal 105 on one or more ofthe first optimal frequency bands.

FIG. 7 is a signal flow diagram for a network arrangement having a firstterminal 105, a second terminal 110, and a network coordinator 135.Again, the network arrangement may include any number of terminals.Also, the network coordinator 135 and the first and second terminals maybe similarly configured devices, such as cellular telephones, RF radios,or other devices configured to transmit and receive data on a wirelesslink.

The network coordinator 135 is tasked with establishing the wirelesslink between the first terminal and the second terminal 110 (see FIG.1B).

In this embodiment, both the first and second terminals 105 and 110transmit (705 and 710) their respective RF spectral information ordesired operating frequency band(s) to the network coordinator 135.Next, the network coordinator 135 negotiates a frequency band for eachof the terminals such that a product or a sum of a forward link and areverse link throughput for each plurality of terminal devices isjointly maximized on the wireless link. The forward and reverse linkthroughput is determined from an analysis of the radio frequency (RF)spectral information for the plurality of terminal devices.

The network coordinator 135 then transmits (715 and 720) to eachterminal device, an optimal frequency band(s) for the other terminaldevices in the network. In this example, the first terminal 105 receivesan optimal frequency band for the second terminal 110 and the secondterminal 110 receives an optimal frequency band for the first terminal105.

Once the optimal frequency bands have been disseminated, the secondterminal 110 transmits 725 signals to the first terminal 105 on one ormore of the optimal frequency bands, while the first terminal 105transmits 730 signals to the second terminal 110 on one or more of theoptimal frequency bands.

FIG. 8 is a flowchart of an exemplary method 800 for transmitting databetween network devices using channel optimization in half duplexcommunications. It will be understood that a first and second terminalare network devices, and more specifically, the first and secondterminals are not co-located with one another. Again, when the terminalsare not co-located, the RF spectral information for these terminals maybe different from one another due to interference, SINR, or any of theother throughput mitigating factors described herein.

Initially, the method 800 includes obtaining 805 at a first terminal,radio frequency (RF) spectral information local to the first terminal.This may include scanning the local area for RF spectral information.

The method 800 also includes an optional step of transmitting 810 the RFinformation to a second terminal. The second terminal may process thisRF spectral information for the first terminal to determine a firstoptimal frequency band for the first terminal. This step 810 is optionalbecause the first terminal may analyze its own RF spectral informationand select one or more preferred frequency bands. These bands may beplaced in a ranked ordered list according to interference plus noiseinformation for each band, and transmitted to the second terminal.

The method 800 also includes analyzing 815 at the first terminal, RFspectral information for a second terminal that is not co-located withthe first terminal. The first terminal may select a second terminaloptimal frequency band for the second terminal. Next, the method 800includes transmitting 820 data to the second terminal on a secondterminal optimal frequency band, as well as receiving 825 data from thesecond terminal on a first terminal optimal frequency band. Again, thefirst terminal optimal frequency may be based upon the RF spectralinformation local to the first terminal.

FIG. 9 is a flowchart of an exemplary method 900 for transmitting databetween network devices using channel optimization in half duplexcommunications. The method is preferably executed by a networkcoordinator, which may include an intermediary network device thatcommunicates with a plurality of terminal devices. Also, the networkcoordinator may include one of a plurality of terminal devices that forma network.

The method 900 includes establishing 905 a wireless link with aplurality of terminal devices. After establishing the wireless link, themethod includes receiving 910 from the plurality of terminal devices,radio frequency (RF) spectral information. Also, the method 900 includesexchanging 915 RF spectral information between the plurality of terminaldevices.

In some instances, the method 900 includes negotiating 920 a frequencyband for each of the plurality of terminal devices such that a productor a sum of a forward link and a reverse link throughput for eachplurality of terminal devices is jointly maximized on the wireless link.Again, the forward and reverse link throughput is determined from ananalysis of the radio frequency (RF) spectral information for theplurality of terminal devices.

In some instances, the network coordinator negotiates an optimalfrequency band for each terminal by analyzing all of the RF spectraldata for the terminals. The network coordinator would then transmit toeach terminal, the optimal frequency for the other terminals in thenetwork. Further, this information would include the optimal receivingfrequency for the terminal.

In other embodiments, the terminals may process their own RF spectralinformation and provide suggested optimal frequency bands to the networkcoordinator. The network coordinator would then resolve any conflictsbetween the terminals and transmit back to the terminals theirrespective optimal frequency band(s), both for transmitting andreceiving of signals with other terminals in the network. Again, eachterminal has an optimal receiving frequency band, but may utilize aplurality of optimal transmitting frequency bands for the other remoteterminals in the network.

FIG. 10 illustrates an exemplary network 1000 having two dual channelterminals that are communicating with one another using the TDD/FDDmethods provided herein. In detail, each of the terminals 1005 and 1010,include a processor 1015 and a memory 1020 for storing executableinstructions. The processor 1015 executes the instructions to performmethods of dual channel optimization as provided below.

For purposes of brevity, it will be understood that the terminals 1005and 1010 are constructed similarly to one another. Furthermore, theseterminals are similar to the terminals of FIGS. 1A and 1B with theexception that they are configured with dual communication interfaces.

For example, both of the terminals 1005 and 1010 each include a timedivision duplexing interface 1025 for transmitting or receiving data ona first channel 1030 and a frequency division duplexing interface 1035for transmitting or receiving data on a second channel 1040. Theterminals 1005 and 1010 transmit data over a wireless link 130, whichcomprises both the first and second channels 1030 and 1040.

Each of the terminals may be configured to determine radio frequency(RF) spectral information local to the terminal. Furthermore, eachterminal may select an optimal frequency band for the first channel 1030based upon the RF spectral information.

Each of the terminals is also configured to select an optimal frequencyband for the second channel 1040 based upon the RF spectral information.

As mentioned previously, rather than the terminal itself determiningoptimal frequency bands for the first and second channels, thisfunctionality may be performed by other terminals in the network or by anetwork coordinator.

In some instances, each of the terminals may transmit management framesthat include the optimal frequency band for the first channel and theoptimal frequency band for the second channel to one or more additionaldevices on the network.

In this embodiment, the terminal 1005 may also be configured to receivedata from another terminal 1010 on either of the first and secondchannels 1030 and 1040, using the desired frequency for each channel.

For devices with dual channel capability, a combination of pure TDD andTDD/FDD modes of operation can be used on each channel. See FIG. 5 foran example of pure TDD mode of operation one channel, and TDD/FDD modeof operation on the second channel. Dynamic channel selection and RFspectrum monitoring can be performed separately for each channel.

Use Case

A point-to-point link of 26.4 miles between two sites in NorthernCalifornia is established between a first terminal and a secondterminal. At the site for each end of the link, the RF spectrum ismeasured.

FIG. 11 plots the time-averaged RF power due to interference plus noiseat each of the two sites, and overlaid on top of each other. This showsthat the RF spectra at two sites can be quite different.

FIG. 12 plots the similar data from the RF spectrum measurements interms of received SINR at each of the two sites. This is correlates tothe achievable MCS and rate in the presence of interference and noise ateach frequency band.

FIG. 13 shows as an example for each of the 80 MHz channels (based onIEEE 802.11ac channels) the effective rate that can be achieved. Toachieve the highest rate at 351 Mbps, there are three 80 MHz channelsavailable at Site 1, and two 80 MHz channels available at Site 2 forTDD/FDD mode of operation. For pure TDD mode of operation, there is onlyone 80 MHz band available. For these two locations, TDD/FDD mode ofoperation is able to provide better throughput and reliability than pureTDD mode of operation.

FIG. 14 illustrates an exemplary computing device 1 that may be used toimplement an embodiment of the present systems and methods. Thecomputing device 1 of FIG. 14 may be implemented in the contexts of thelikes of computing devices, radios, terminals, networks, servers, orcombinations thereof. The computing device 1 of FIG. 14 includes aprocessor 10 and main memory 20. Main memory 20 stores, in part,instructions and data for execution by processor 10. Main memory 20 maystore the executable code when in operation. The computing device 1 ofFIG. 14 further includes a mass storage device 30, portable storagedevice 40, output devices 50, user input devices 60, a display system70, and peripherals 80.

The components shown in FIG. 14 are depicted as being connected via asingle bus 90. The components may be connected through one or more datatransport means. Processor 10 and main memory 20 may be connected via alocal microprocessor bus, and the mass storage device 30, peripherals80, portable storage device 40, and display system 70 may be connectedvia one or more input/output (I/O) buses.

Mass storage device 30, which may be implemented with a magnetic diskdrive or an optical disk drive, is a non-volatile storage device forstoring data and instructions for use by processor 10. Mass storagedevice 30 can store the system software for implementing embodiments ofthe present technology for purposes of loading that software into mainmemory 20.

Portable storage device 40 operates in conjunction with a portablenon-volatile storage medium, such as a floppy disk, compact disk ordigital video disc, to input and output data and code to and from thecomputing device 1 of FIG. 14. The system software for implementingembodiments of the present technology may be stored on such a portablemedium and input to the computing device 1 via the portable storagedevice 40.

Input devices 60 provide a portion of a user interface. Input devices 60may include an alphanumeric keypad, such as a keyboard, for inputtingalphanumeric and other information, or a pointing device, such as amouse, a trackball, stylus, or cursor direction keys. Additionally, thecomputing device 1 as shown in FIG. 14 includes output devices 50.Suitable output devices include speakers, printers, network interfaces,and monitors.

Display system 70 may include a liquid crystal display (LCD) or othersuitable display device. Display system 70 receives textual andgraphical information, and processes the information for output to thedisplay device.

Peripherals 80 may include any type of computer support device to addadditional functionality to the computing system. Peripherals 80 mayinclude a modem or a router.

The components contained in the computing device 1 of FIG. 14 are thosetypically found in computing systems that may be suitable for use withembodiments of the present technology and are intended to represent abroad category of such computer components that are well known in theart. Thus, the computing device 1 can be a personal computer, hand heldcomputing system, telephone, mobile computing system, workstation,server, minicomputer, mainframe computer, or any other computing system.The computer can also include different bus configurations, networkedplatforms, multi-processor platforms, etc. Various operating systems canbe used including UNIX, Linux, Windows, Macintosh OS, Palm OS, and othersuitable operating systems.

Some of the above-described functions may be composed of instructionsthat are stored on storage media (e.g., computer-readable medium). Theinstructions may be retrieved and executed by the processor. Someexamples of storage media are memory devices, tapes, disks, and thelike. The instructions are operational when executed by the processor todirect the processor to operate in accord with the technology. Thoseskilled in the art are familiar with instructions, processor(s), andstorage media.

It is noteworthy that any hardware platform suitable for performing theprocessing described herein is suitable for use with the technology. Theterms “computer-readable storage medium” and “computer-readable storagemedia” as used herein refer to any medium or media that participate inproviding instructions to a CPU for execution. Such media can take manyforms, including, but not limited to, non-volatile media, volatile mediaand transmission media. Non-volatile media include, for example, opticalor magnetic disks, such as a fixed disk. Volatile media include dynamicmemory, such as system RAM. Transmission media include coaxial cables,copper wire and fiber optics, among others, including the wires thatcomprise one embodiment of a bus. Transmission media can also take theform of acoustic or light waves, such as those generated during radiofrequency (RF) and infrared (IR) data communications. Common forms ofcomputer-readable media include, for example, a floppy disk, a flexibledisk, a hard disk, magnetic tape, any other magnetic medium, a CD-ROMdisk, digital video disk (DVD), any other optical medium, any otherphysical medium with patterns of marks or holes, a RAM, a PROM, anEPROM, an EEPROM, a FLASHEPROM, any other memory chip or data exchangeadapter, a carrier wave, or any other medium from which a computer canread.

Various forms of computer-readable media may be involved in carrying oneor more sequences of one or more instructions to a CPU for execution. Abus carries the data to system RAM, from which a CPU retrieves andexecutes the instructions. The instructions received by system RAM canoptionally be stored on a fixed disk either before or after execution bya CPU.

Computer program code for carrying out operations for aspects of thepresent technology may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present technology has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Exemplaryembodiments were chosen and described in order to best explain theprinciples of the present technology and its practical application, andto enable others of ordinary skill in the art to understand theinvention for various embodiments with various modifications as aresuited to the particular use contemplated.

Aspects of the present technology are described above with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present technology. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. The descriptions are not intended to limit the scope of thetechnology to the particular forms set forth herein. Thus, the breadthand scope of a preferred embodiment should not be limited by any of theabove-described exemplary embodiments. It should be understood that theabove description is illustrative and not restrictive. To the contrary,the present descriptions are intended to cover such alternatives,modifications, and equivalents as may be included within the spirit andscope of the technology as defined by the appended claims and otherwiseappreciated by one of ordinary skill in the art. The scope of thetechnology should, therefore, be determined not with reference to theabove description, but instead should be determined with reference tothe appended claims along with their full scope of equivalents.

What is claimed is:
 1. A method for transmitting data between networkdevices using channel optimization in half duplex communications, themethod comprising: obtaining at a first terminal, radio frequency (RF)spectral information local to the first terminal; analyzing at the firstterminal, RF spectral information for a second terminal that is notco-located with the first terminal; transmitting data to the secondterminal on a second terminal optimal frequency band; receiving datafrom the second terminal on the first terminal optimal frequency band,the first terminal optimal frequency being based upon the RF spectralinformation local to the first terminal; and wherein selecting at thefirst terminal a first terminal optimal frequency band includesanalyzing the RF spectral information for the first terminal todetermine a signal-to-noise ratio, an error vector magnitude, aninterference plus noise power spectrum, and an overlapping basic serviceset traffic activity.
 2. A dual channel network device, comprising: atime division duplexing interface for transmitting or receiving data ona first channel; a time division duplexing and frequency divisionduplexing interface for transmitting or receiving data on a secondchannel; a processor; and a memory for storing executable instructions,the processor executing the instructions to perform operationscomprising: determining radio frequency (RF) spectral information localto the device; selecting at the device an optimal frequency band for thefirst channel based upon the RF spectral information; selecting at thedevice an optimal frequency band for the second channel based upon theRF spectral information; transmitting management frames that include theoptimal frequency band for the first channel and the optimal frequencyband for the second channel to one or more additional devices on anetwork; and receiving data from the one or more devices on either ofthe first and second channels.
 3. A terminal device, comprising: aprocessor; and a memory for storing executable instructions, whereinexecution of the instructions causes the processor to: determine radiofrequency (RF) spectral information local to the terminal device;analyze spectral information for one or more additional terminal devicesin a network that are not co-located with the terminal device; determinean optimal frequency band for each of the one or more additionalterminal devices; transmit data to the one or more additional terminaldevices using a the optimal frequency bands; and receive data from theone or more additional terminal devices on an optimal frequency bandthat is based upon the RF spectral information local to the terminaldevice; and wherein the terminal device is further configured todetermine an optimal frequency band for each of the one or moreadditional terminal devices by analyzing RF spectral information foreach of the one or more additional terminal devices to determine asignal-to-noise ratio, an error vector magnitude, an interference plusnoise power spectrum, and an overlapping basic service set trafficactivity.